Compression holder

ABSTRACT

A tool holder having a cylindrical outer housing adapted to be inserted into a chuck of a rotary drive mechanism. A tool supporting rod is axially slidably mounted in a bore formed in the housing for rotation about its axis of elongation. A coil spring disposed within the bore between the inner end of the tool supporting rod and the closed end of the bore biases the rod toward an extended position. During the feed-in of the machine chuck in the deburring of holes, the coil spring can be compressed to permit the tool to be retracted when the deburring tool engages an unfinished hole resulting from drill breakage to thereby prevent the deburring tool from being forced into the unfinished hole and thereby broken.

United States Patent Kubicek 41 COMPRESSION HOLDER [72] Inventor: LouisA. Kubicek, Ypsilanti, Mich.

[73] Assignee: Burr-Ban Tool Service Company, Detroit,

Mich.

221 Filed: Dec. 22, 1969 [21] Appl.No.: 887,059

[52] U.S. Cl ..408/239, 408/228, 408/714 [51 I Int.Cl r ..B23b5l/l6 [58]Field ofSearch ..77/73.5;408/228, 239,714

[56] References Cited UNITED STATES PATENTS 3,230,798 1/1966 Kubicek eta1 ..77/73.5

OTHER PUBLICATIONS Publication: IBM Technical Disclosure Bulletin, Vol.6, No. 8,

[451 Apr.-25, 1972 January 1964, page 15, article entitled Quick ActionCoun' tersink" by R. Deporto and J. Saxon Primary E.raminer-Francis S.Husar Attorney-Hauke, Gifford and Patalidis ABSTRACT A tool holderhaving a cylindrical outer housing adapted to be inserted into a chuckofa rotary drive mechanism. A tool supporting rod is axially slidablymounted in a bore formed in the housing for rotation about its axis ofelongation. A coil spring disposed within the bore between the inner endof the tool supporting rod and the closed end of the bore biases the rodtoward an extended position. During the feed-in of the machine chuck inthe deburring of holes, the coil spring can be compressed to permit thetool to be retracted when the deburring tool engages an unfinished holeresulting from drill breakage to thereby prevent the deburring tool frombeing forced into the unfinished hole and thereby broken.

6 Claims, 4 Drawing Figures PATENTEDAPRZS I972 3, 6 58 43 5 FIG- IINVENTOR LOUIS A. KUBICEK aYA M, @7 4 FM ATTORNEYS BACKGROUND OF THEINVENTION l. Field of the Invention The invention relates to toolholders and more particularly to a tool holder having means permittingthe tool carried thereby to be moved from a normal extended position toa retracted position to prevent tool breakage.

2. Description of the Prior Art operation.

In the drilling and deburring of holes in workpieces, often times thehole is drilled and immediately thereafter the edges of the hole aredeburred. Usually in these types of operations the workpiece is passedin front of several machine chucks having the necessary tools to performthe drilling and deburring operation. Frequently, the drilling anddeburring operations are out of view of the machine operator and pass infront of the operator only after both operations have been completed.When a drill is accidentally broken during the drilling operationresulting in an unfinished hole, the workpiece automatically advances tothe next station where the deburring operation takes place without theoperator detecting that a drill has broken. As the deburring tool isadvanced into the unfinished hole, the end of the deburring tool engagesthe inner surface of the unfinished hole and is broken thereby,necessitating the replacement of not only the broken drill but also thebroken deburring tool.

SUMMARY OF THE INVENTION The tool holder of the present invention solvesthe problems of the prior art devices by providing a resilient memberbetween the machine chuck and the deburring tool which absorbs thefeed-in of the chuck when thedeburring tool engages an unfinished hole.The tool includes a cylindrical outer housing for insertion into thechuck of a rotary drive machine for rotation about its axis ofelongation. The outer housing includes a cylindrical bore formed thereinparallel to the axis of elongation of the housing and closed at one end.A tool supporting rod having an end portion axially slidably mountedwithin the bore of the outer housing has an elongated slot formedtherein parallel to the axis of elongation of the rod.

The outer housing includes a radially directed threaded aperture formedadjacent the bore opening for receiving a screw having a cylindricalprojection formed on its inner end. The projection extends into theelongated slot of the rod, rotating the rod about its axis of elongationas the housing is rotated, but not inhibiting the axial movement of therod. A coil spring disposed within the bore between the inner end of therod and the closed end of the bore biases the rod toward the boreopening. A collet is secured to the outer end of the rod for securing adeburring tool thereto.

A deburring tool, preferably including a pair of parallel arms eachhaving a radially extending cutting lobe formed thereon, is secured forrotation to the outer end of the rod by the collet. As the holder anddeburring tool are rotated by the drive machine, the deburring tool ismoved into the hole in the workpiece to be deburred. If the hole in theworkpiece has not been completely formed due to the drill having beenpreviously broken, the end of the deburring tool engages the inner endof the unfinished hole or the upper surface of the workpiece and furtherfeed-in by the drive machine pushes the rod into the bore, compressingthe spring therein and preventing the deburring tool form being brokenby the feed-in of the drive machine. Thus, even if the hole in theworkpiece has not been completely formed, the deburring tool is notbroken by the feed-in of the drive machine.

DESCRIPTION OF THE DRAWINGS The description refers to the accompanyingdrawings wherein like reference characters refer to like partsthroughout the several views and in which:

FIG. I is a side elevational view of a preferred embodiment of thepresent invention;

FIG. 2 is a cross sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a side elevational view showing the deburring tool beingpushed intoan unfinished hole in the workpiece; and

FIG. 4 is a cross sectional view taken on line 44 of FIG. 1 showing theadjustment mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a toolholder, generally indicated at 10, is adapted to carry a deburring tool,generally indicated at 12, such that the tool holder and the deburringtool 12 are rotated about their axes of elongation by the chuck of asuitable rotary drive machine (not shown).

The tool holder 10, as shown in FIGS. 1 and 2, includes an outercylindrical housing 14 which has threads 16 formed along its outersurface for receiving an adjustment collar 18 screwed thereon. Theadjustment collar 18 is provided with a set screw 20 (FIG. 2) threadedinto an aperture 22 formed therein for locking the collar on the housing14 at the desired axial position. When the outer housing 14 is insertedinto the chuck of a rotary drive machine, the collar 18 engages thefront surface of the chuck to provide an adjustable stop to axiallylocate the housing 14 with respect to the chuck.

As can best be seen in FIG. 2a portion of the threads 16 are ground awayto provide a fiat surface 24 which receives a set screw (not shown)carried by the chuck of the drive machine to secure the outer housing 14in the chuck. A Woodruff key slot 26 is formed in the housing 14adjacent the rear end 28. The slot 26 receives a Woodruff key (notshown) carried by the machine chuck for rotatably driving the outerhousing 14 about its axis of elongation.

The outer housing 14 is formed with a cylindrical bore 30 extendingparallel to the axis of elongation of the outer housing and having aclosed inner end formed by upper surface 32. A tool supporting rod 34having an end portion slidably mounted within the bore 30 is formed withan enlarged inner end 36. The inner end 36 forms a bearing surfaceengaging the inner surface forming the bore 30 to facilitate axialsliding movement of the rod 34 within the bore 30. A cylindrical collet40 slidably mounted around the rod 34 and formed with a slightly smallerouter diameter than the bore 30 is positioned within the bore 30adjacent the bore opening 42 for providing asecond bearing surface forthe rod 34. The collet 40 includes an annular flange 44 which extendsradially outwardly from the outer end of the collet so as to engage thefront surface 46 of the housing 14, aiding in the positioning of thecollet within the bore 30.

Still referring to FIG. 2 the housing 14 is formed with a radiallydirected threaded aperture 48 adjacent the bore opening 42 for receivinga screw 50 formed with a cylindrical projection 52 on its inner end. Theprojection 52 extends through an aperture 54 formed in the collet 40,securing the collet 40 against axial or rotary movement relative to thehousing 14. The rod 34 is formed with an elongated slot 56 substantiallyparallel to the axis of elongation of the rod 34 for receiving the endof the projection 52. Thus, as the housing 14 is rotated by the machinechuck, the projection 52 engages the surface forming the slot 56 torotate the rod about its axis of elongation but does not prevent the rod34 from sliding axially within the bore 30.

A coil spring 58 disposed within the bore 30 is compressed between theinner surface 60 of the inner end 36 and the surface 32, urging the rod34 toward the bore opening 42.

Still referring to FIG. 2, a collet 62 is positioned around the outerend of the rod 34 and includes a pair of radially directed threadedapertures 64 and 66 formed therein for receiving set screws 68 and 70,respectively. The inner end of the set screw 68 engages a flat surface72 formed on the outer end of the rod 34 for securing the colletthereto. The upper end of the shank 71 of the deburring tool 12 isinserted into the other end of the collet 62 and secured therein bymeans of the set screw 70, engaging a flat surface 73 on the shank 71,thus, securing the tool 12 to the rod 34.

The deburring tool 12, as illustrated in FIGS. 1, 3 and 4, and as shownand described in more detail in my U.S. Pat. No. 3,230,798, issued Jan.25, 1966, is preferably formed with a longitudinally extending tensionslot 75 forming a pair of substantially parallel and symmetrical supportcolumns 74. Substantially arcuate cutting ridges or lobes 76 arepreferably formed on the periphery of each of the support columns 74.The cutting ridges 76 are spaced axially somewhat from the free ends ofthe support columns 74 to form a pilot portion 78 to aid in theinsertion of the deburring tool 12 into the hole 80 (FIG. 3) of theworkpiece 82 to be deburred. The cutting ridges 76 are provided withsubstantially radially extending flat surface portions 84. These aredisposed in substantially parallel planes on opposite sides of thedeburring tool 12 and provide sharp cutting edges 86 at each side ofridges 76.

A collar 88 is slidably mounted around the support columns 74 and isretained in position by means of a set screw 90 integrally carrying apin 92 disposed to extend inwardly into the tension slot 75, as is shownin FIG. 4. When the set screw 90 is tightened against the outer surfaceof the support columns 74, the pin 92 provides a fulcrum for the supportcolumns 74 at the point of adjustment so that the flexibility of thesupport columns will depend upon the longitudinal position of the collar88.

In operation, the shank 71 of the deburring tool 12 is secured in thecollet 62 by set screw 70. The adjustment collar 18 is then positionedon the housing 14, setting the distance the housing 14 and the tool 12extend from the machine chuck. A Woodruff key is then inserted into theslot 26 and the rear portion of the housing 14 is inserted into themachine chuck with the face of the chuck flush with the collar 18. Thehousing 14 is secured therein by turning a set screw against the surface24. As positioned, the holder and the tool 12 are rotated about theiraxes of elongation by the chuck of the rotary drive machine.

Referring to FIG. 3, as the deburring tool 12 is advanced toward thehole 80 to be deburred, the pilot portion 78 enters the hole 80. if thehole 80 has been properly formed to a sufficient depth, the bottomcutting edges 86 of the ridges 76 engage the upper edge 94 with therotary motion of the tool 12 deburring the edge 94.

If the hole 80 has been properly formed completely through the workpiece82, the tool 12 continues to advance and the arms 74 are pushed togetherby the engagement of the ridges 76 and the hole 80, allowing the ridges76 and a portion of the arms 74 to pass through the hole 80 to deburrthe bottom edge of the hole. When the ridges 76 have cleared the hole80, the arms 74 spring back to their original position, ready to deburrthe back edge of the hole 80 on the back stroke of the drive machine.

If the hole 80 has not been properly formed to a sufficient depth due tobreakage of the drill or the like, as the deburring tool 12 is advancedtoward the hole to be deburred the pilot portion 78 enters the hole. Asthe tool 12 continues to be fed into the hole 80 by the drive machine,the pilot portion 78 engages the inner end 96 of the unfinished hole 80or engages the upper surface of the workpiece if no hole at all has beenformed, stopping the advancement of the tool 12. The continued feed-inof the drive machine pushes the rod 34 into the bore 30, compressing thespring 58. The rod 34 slides upon the bearing surface formed between theinner end 36 and the bore 30 and the bearing surface formed between therod 34 and the collet 40. As the rod 34 is pushed into the bore 30, theinner end of the projection 52 slides along in the slot 56 formed in therod 34, thus, permitting the rod to be retracted into the bore 30 evenwhile the tool continues to rotate. As the housing 14 is rotated by themachine chuck, the screw 50 is turned, rotating the rod 34 about itsaxis by the engagement of the projection 52 and the slot 56. As the rod34 is pushed into the bore 30, the coil spring 58 is compressed betweenthe inner surface 60 of the rod 34 and the surface 32 of the housing 14.The compression of the spring 58 during the feed-in of the machine chuckallows the deburring tool 12 to remain with its pilot portion 78 incontact with the inner end 96 without pushing the deburring tool 12further into the unfinished hole 80. Thus, the tool holder It) preventsthe deburring tool 12 from being broken during the feed-in of the drivemachine when the hole has not been properly formed in the workpiece.

It is to be noted that the strength of the spring 58 may be varied inaccordance with the strength of the support columns 74, such that, whenthe support columns 74 are weak a weak spring 58 is used. Thus, when thetool 12 is advanced into an unfinished hole 80, the support columns 74are strong enough to compress the spring 58, thereby preventing the tool12 from being broken. Furthermore, the strength of the spring 58 may bereadily varied with the positioning of the collar 88. As the collar 88is moved toward the ridges 76 an increased force is required to push thesupport columns 74 together to allow the ridges 76 to be pushed into thehole 80. Thus, as the collar 88 is moved toward the ridges 76 a strongerspring 58 may be used.

Finally, if it is desired to obtain a longer dwell of the cutting edges86 on the edge 94 than is permitted by the feed-in rate of the drivemachine, the strength of the spring 58 may be varied such that as thetool 12 is advanced into the hole 80 the spring 58 is compressed,allowing the cutting edges 86 to remain in contact with the edge 94. Thespring 58 is compressed until it develops enough force to push thesupport columns 74 together and allow the ridges 76 to pass into thehole 80. Thus, the tool holder 10 may not only be used to preventbreakage of the deburring tool 12 but can also be used to provide for alonger deburring dwell on the leading edge of a hole.

Although the deburring tool 12 is illustrated with two substantiallyparallel columns 74 and a cutting ridge 76 on each column with radiallyextending cutting edges 86, it is to be understood that the tool may bereplaced by a cutting tool having two arms and a cutting ridge on onlyone of the arms, as is generally illustrated in my U.S. Pat. No.3,276,294. Alternatively, the radially extending cutting edges 86 may bereplaced with a cutting edge along the top of the cutting ridge 76extending generally parallel to the axis of elongation of the tool fordeburring inside a hole. Although the tool 12 is illustrated with anadjustment collar 88, it is to be understood that a different mechanismmay be used to adjust the tension of the tool columns 74, such as atransversely extending pin within the slot 75, as is illustrated in myU.S. Pat. No. 3,41 l,386.

Although I have described but one preferred embodiment of my invention,it is to be understood that various changes and revisions may be madetherein without departing from the spirit of the invention or the scopeof the appended claims.

lclaim:

l. The combination of a compression tool holder and a deburring toolcomprising:

a cylindrical housing having a bore formed therein,

a tool holding rod connected to a deburring tool means and having aportion extending from within said bore to a point axially spaced fromsaid housing,

said tool holding rod having an exterior surface and a straight, axiallyextending elongated slot formed in said exterior surface,

means carried by said housing and limiting outward axial movement ofsaid deburring tool means,

a pin carried by said housing and extending into said slot to precluderelative rotation between said housing and said deburring tool means butsaid pin and slot permit said deburring tool means to move axially withrespect to said housing, and

a spring carried in said bore and urging said deburring tool meansaxially outwardly to the limit permitted by said limiting means.

2. The combination as defined in claim 1, and including a cylindricalcollet slidably mounted around said tool holding rod within said boreadjacent the opening of said bore, said collet being secured to saidhousing for forming a bearing surface with said tool holding rod.

3. The combination as defined in claim 1 and in which said deburringtool means comprises a first shank portion extending from said toolholding rod, a second shank portion having cutting means at one endthereof and means for axially coupling said tool holding rod to the freeend of said first shank portion.

4. The combination as defined in claim 3 and in which said second shankportion comprises a pair of spaced apart arms and including meanscarried by said shank portion for varying the effective length of saidarms.

5. The combination as defined in claim 3, wherein said last mentionedmeans includes a collar adjustably longitudinally slidably mountedaround said arms, and means carried by said collar and extending betweensaid arms for providing a fulcrum between said arms which varies theeffective length of said arms.

6. The combination as defined in claim 1 and in which said limitingmeans comprises a cylindrical collet extending into said bore and meansfor securing said collet to said housing, said tool holding rod beingpositioned within said bore and engaging with the end of said collet tothereby limit outward movement of said deburring tool means.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CQRRCTION patent No, 9 94Dated April 25 1972 Inventor(s) Louis Av icek It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below Column 1,, line 63, after "tool" delete"form" and insert "from-=- Signed and sealed this 19th day of September1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of PatentsAttesting Officer USCOMM-DC 60376-P69 FORM PO-105O (10-69) w u .s,eovsnumzm' PRINTING OFFICE: I969 0-356-334

1. The combination of a compression tool holder and a deburring toolcomprising: a cylindrical housing having a bore formed therein, a toolholding rod connected to a deburring tool means and having a portionextending from within said bore to a point axially spaced from saidhousing, said tool holding rod having an exterior surface and astraight, axially extending elongated slot formed in said exteriorsurface, means carried by said housing and limiting outward axialmovement of said deburring tool means, a pin carried by said housing andextending into said slot to preclude relative rotation between saidhousing and said deburring tool means but said pin and slot permit saiddeburring tool means to move axially with respect to said housing, and aspring carried in said bore and urging said deburring tool means axiallyoutwardly to the limit permitted by said limiting means.
 2. Thecombination as defined in claim 1, and including a cylindrical colletslidably mounted around said tool holding rod within said bore adjacentthe opening of said bore, said collet being secured to said housing forforming a bearing surface with said tool holding rod.
 3. The combinationas defined in claim 1 and in which said deburring tool means comprises afirst shank portion extending from said tool holding rod, a second shankportion having cutting means at one end thereof and means for axiallycoupling said tool holding rod to the free end of said first shankportion.
 4. The combination as defined in claim 3 and in which saidsecond shank portion comprises a pair of spaced apart arms and includingmeans carried by said shank portion for varying the effective length ofsaid arms.
 5. The combination as defined in claim 3, wherein said lastmentioned means includes a collar adjustably longitudinally slidablymounted around said arms, and means carried by said collar and extendingbetween said arms for providing a fulcrum between said arms which variesthe effective length of said arms.
 6. The combination as defined inclaim 1 and in which said limiting means comprises a cylindrical colletextending into said bore and means for securing said collet to saidhousing, said tool holding rod being positioned within said bore andengaging with the end of said collet to thereby limit outward movementof said deburring tool means.